Infrared Absorption Studies of <i>n</i>-Heptane under High Pressure

Yamaguchi, Masashi; Serafin, Scott V.; Morton, Thomas Hellman; Chronister, Eric L.

doi:10.1021/jp0221439

Cited by 26 publications

(52 citation statements)

References 28 publications

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“…High‐pressure Raman scattering studies at ambient temperature were performed on n ‐heptane, which remained stable over the entire range of pressures. A liquid‐solid transition occurred at a pressure of approximately 1.5 GPa ,,. At 7.5 GPa, changes in the Raman modes and the spectra were interpreted as the solid‐solid transition …”

Section: Experimental Studies Of Individual Hydrocarbon Transformationsmentioning

confidence: 99%

Chemistry of Hydrocarbons Under Extreme Thermobaric Conditions

2017

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What will happen when methane is at a temperature of 1500 K? On the first glance the answer seems to be obvious ‐ methane will decompose into hydrogen and one of the forms of carbon. Yes. However is does not do so at very high pressure, when novel reaction pathways become possible. The latest experimental results and theoretical calculations show that methane and heavier hydrocarbons are, remarkably enough, stable under extreme pressures and temperatures. Even more, experiments confirm the possibility of abiogenic synthesis of natural gas at 5.0 GPa and 1500 K. The review summarizes published results of theoretical and experimental investigations of possible pathways under the conditions of pressure and temperature that prevail in the Earth's upper mantle for the formation of (1) particular species of hydrocarbon molecules, and of (2) complex hydrocarbon systems. The results raise fundamental questions on the genesis of hydrocarbons.

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Section: Experimental Studies Of Individual Hydrocarbon Transformationsmentioning

confidence: 99%

Chemistry of Hydrocarbons Under Extreme Thermobaric Conditions

2017

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“…Figure 6a shows the intensity ratio of I 1130 /I 1090, which is a representation of the population of trans and gauche conformers. [23][24][25][26][27][28] The I 1130 /I 1090 intensity ratio increases with increase in pressure suggesting an increase in TT (all-trans) population. These modes cease to exist beyond 12.3 GPa because of a possible phase transition.…”

Section: Methyl Rocking Regionmentioning

confidence: 99%

Pressure-Induced Structural Transition in n-Pentane: A Raman Study

Ganesan

Narayana

2007

J. Phys. Chem. B

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Pressure-induced Raman spectroscopy studies on n-pentane have been carried out up to 17 GPa at ambient temperature. n-Pentane undergoes a liquid-solid transition around 3.0 GPa and a solid-solid transition around 12.3 GPa. The intensity ratio of the Raman modes related to all-trans conformation (1130 cm-1 and 2850 cm-1) to that of gauche conformation (1090 cm-1 and 2922 cm-1) suggests an increase in the gauche population conformers above 12.3 GPa. This is accompanied with broadening of Raman modes above 12.3 GPa. The high-pressure phase of n-pentane above 12.3 GPa is a disordered phase where the carbon chains are kinked. The pressure-induced order-disorder phase transition is different from the behavior of higher hydrocarbon like n-heptane.

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“…Infrared absorption experiments performed over a pressure range from ambient to 7 GPa revealed that n -heptane undergoes a liquid to solid transition at 11.8–14.9 GPa and a possible solid–solid transition at near 3 GPa. 10 Since then, molecular dynamic simulation calculations of n -heptane have confirmed the existence of the liquid–solid transition at 1.2–1.5 GPa. 11 Recent Raman spectroscopic investigations carried out up to a pressure of 16 GPa have indicated that a liquid–solid and a solid–solid phase transition happen at around 1.5 GPa and 7.5 GPa, respectively.…”

Section: Introductionmentioning

confidence: 98%

In Situ High-Pressure and High-Temperature Experiments on n-Heptane

Qiao

Zheng²,

Long³

2012

Appl Spectrosc

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The Raman spectroscopy of n-heptane was investigated in a moissanite anvil cell at ambient temperatures and a diamond anvil cell under pressures of up to ~2000 MPa and at temperature range from 298 to 588 K. The results show that at room temperature the vibration modes, assigned to the symmetric and antisymmetric stretching of CH(3) and CH(2) stretching, shifted to higher frequency according to quasi-linearity with increasing pressure, and a liquid-solid phase transition occurred at near 1150 MPa. The high-temperature solidus line of n-heptane follows a quadratic function of P = 0.00737T(2) + 5.27977T - 1195.76556. Upon phase change, fitting the experimental data obtained in the temperature range of 183∼412 K to the Clausius-Clapeyron equation allows one to define the thermodynamic parameters of n-heptane of dP/dT = 0.01474T + 5.27977.

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Infrared Absorption Studies of n-Heptane under High Pressure

Cited by 26 publications

References 28 publications

Chemistry of Hydrocarbons Under Extreme Thermobaric Conditions

Chemistry of Hydrocarbons Under Extreme Thermobaric Conditions

Pressure-Induced Structural Transition in n-Pentane: A Raman Study

In Situ High-Pressure and High-Temperature Experiments on n-Heptane

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